Shock absorbing machine gun mount



J. C. TROTTER SHOCK ABSORBING MACHINE GUN MOUNT Dec. 30, 194,7.

Filed oct. 19, 1945 4 Sheets-Sheet l I c7 C 5M @M @la Dec. 30, 1947. J. c. TROTTER SHOCK ABSORBING MACH-INE GUN MOUNT Filed oct. 19, 1945 4 sheets-sheet 2 E n Nm 5,. wm

mm Q, a, 8

mvEN-roR J3 Jon-m C. Tam-TE@ www;

Dec. 3o, 1947. Y J 3, TROTTER 2,433,331

SHOCK ABSORBING MACHINE GUN MOUNT Filed oct. 19, 1945 4 sheets-sheet 3 Ho 5012291.43* I Dec. 30, j C, TRO-ITER 2,433,637

SHOCKfABSORBING MACHlNE GUN MOUNT Filed Oct. 19, 1945 4 Sheets-Sheet 4 NVENTOR am. Mmw mmm Patented Dec. 30, 1947 UNITED STATE`SPATENT OFFICE SHOCK ABSORBING MACHINE GUN MOUN'` John C. Trotter, Burlington, Vt., assigner to Bell Aircraft Corporation, Wheatield, N. Y.

Application October 19, 1945, Serial No. 623,304

4 Claims. 1

This invention relates to automatic guns, and more particularly to improved recoil shock absorbing and damping mechanisms and gun lire rate and vibration control means therefor; and this present application is a continuation-inpart of my abandoned 382,549 i'lled March 10, 1941.

One of the objects of the invention is to provide in a reciprocating bolt action type machine gun or the like a novel gun recoil and counterrecoil control mechanism whereby to reduce the reaction forces acting against the gun mounting structure.

Another object of the invention is to provide in conjunction with a gun of the specified type a recoil control mechanism so constructed and arranged as to thereby provide an increased rate of firing for the attached gun. Another object of the invention is to provide an improved and structurally simple and rugged and inexpensively manufactured device for the purpose described.

Anothel` object of the invention is to provide a device of the character described which is capable of dissipating recoil energy of machine guns in an improved manner.

Other objects and advantages of the invention will appear in the specication hereinafter.

In the drawings:

Fig, 1 is a plan of a machine gun provided with a recoil absorbing and damping mechanism of the invention;

Fig. 2 is a fragmentary side elevation, on. an enlarged scale, of the recoil damping mechanism oi Fig. 1;

Fig. 3 is a section on an enlarged scaletaken substantially along line III-III of Fig. 1;

Fig. 4 isa fragmentary side elevation of the mechanism of Fig. 1, on an enlarged scale, showing the gun bolt diagrammatically and portions of the recoil shock absorbing mechanism thereof in vertical section;

Fig. 5 is a fragmentary plan of another form oi recoil damping device of the mechanism of the invention;

Fig. 6 is a fragmentary side elevation oi the device of Fig. 5;

Fig. 7 is an oscillograph record reproduction showing results of a test of the gun :tiring rate and recoil force reactions against the mounting structure in the case of a standard machine gun arrangement; and

Fig. 8 is a View similar to Fig. 7 showing the testing results subsequent to application'of the present invention to the same type gun and gun mount arrangement,

application Serial No. l

The invention is illustrated in Figs. 1 to 4 in connection with a machine gun having a casing designated generally at I 0 and may be of any type or style that employs a reciprocating bolt as indicated at II. It will be understood that the bolt reciprocates relative to the gun casing I 0 incidental to each gun iiring operation to eiect extraction of the empty cartridge case and to initiateA actions of the recharging and loading and cooking mechanisms. The gun is illustrated as being slidably mounted adjacent its rear end upon a support comprising a pair of parallel bearer tubes I2 by means of a transverse bracket I4 havinglooped portions I5 slidably engagingV the bearer tubes I2. Adjacent its muzzle end, the Vgun I0 is connected to a pair of parallel lugs I8 by means oi a bolt I9. The lugs I8 are formed integrally with a transverse bracket 20 which extends into screwthreaded relation at 2| with a piston rod 22. The piston rod 22 is provided with enlarged heads 24 and 25 at its opposite ends which engage in piston-cylinder relationship with corresponding cylinder portions 26 and 2l respectively of a bracket 28'that is mounted at its forward end by means of a boss connection 29 of a bar 30 extending transversely of the tubes I 2-I2 at their forward ends. The cylinder portion 21 (Fig. 4) is closed at its outer end by means of a screw plug 3I, and a shock pad 32 is seated therewithin to protect the plugv 3I from impact with the piston head 24 during gun recoil operations. An extending stub portion 33 of the plug 3I is engaged through a transverse bracket 34 which extends between the bearer tubes I2-I2 to support the rear end of the cylinder bracket 28. The cylinder portion 26 is closed at its outer end by means of a closure plug 35 which is seated upon the cylinder 26 in substantially airtight fashion. The piston heads 24 and 25 are provided with oppositely directed cup washers 36 which are retained thereon by means of nuts 31. The cup washers 36 are so arranged as to be adapted to expand radially into close tting relation with respect to the corresponding cylinder walls upon piston movement toward the closed end portions of the cylinders, and to contract upon reverse movements thereof. A compression spring 4I] is mounted about the piston rod 22 so as to bear at one of its ends against thesbracket 20 and at the other of its ends against an annular shoulder 4I which extends from the cylinder 2'I.

Thus, starting from a position of rest as illustrated in Figs. 1, 2 and 4, the gunY I @l is'adapted to move rearwardly relative to the bearer tubes |2-I2 under the recoil forces of the gun firing operation, whereupon the recoil forces of the gun are transmitted through the bracket 20 and against the spring 40 which in turn bears against the stationary bracket 28. Thus, the piston moves rearwardly within the cylinder 2l and compresses the air between the piston head 24 and the closure plug 3|, and the air trapped within the cylinder 2l functions to cusnionthe recoil forces of the gun in the manner of the operation of a dash-pot device. Simultaneously, the spring 40 compresses to further cushion the recoil stroke. In the meantime ,the piston .head A25 moves within the cylinder 25 away vfrom the closure plug 35, and air is drawn into -the :cylinder 25 about the washer 36 of `the pistonhead 25. Upon completion of therecoil stroke of the gun the air compressed within the cylinder A21 and the spring 40 operate to urge the piston rod to move in reverse direction so as to return the gun to its initial position. During .the return stroke of lthe gun the air entrapped Withinfthe cylinder 2B behind the washer 36 of .thehea'd25 functions to cushion the return forces so as to prevent damage to the working parts of A the mechanism.

To control the rate ofgunre and toireduce therecoil force reactions against the gun mounting vstructure I provide a novel control mechanism which Yis illustrated in the drawings as Ycornprising a pair of opposed frictiondev'ices 51) which are disposed at opposite sides of the gun. The friction devices 50 are mounted upon `a bolt `52 which extends transversely through .the .cylinder bracket 28 and is mounted thereon by means of .a pair of opposed bearing blocks .54. The bearing blocks are externally squared for mounting in keyed relation within a similarly shapedtaperture formed in the bracket 28. The bearing `blocks 54 are formed with radially extending angeportions 55 which in side elevation -areof discelike form. A friction disc 55 is mounted externally .of each of the ilange portions 55 and ,in.abutting relation thereagainst, and ahousingdisc 5.8 is mounted externally of eaohof the friction discs 56. The housing discs are peripherally flanged as at 5S so as to provide asubstan'tially enclosed friction disc assembly.

While the bearing blocks 54 are keyed within the bracket 25 against rotation about .the bolt 52 as explained hereinabove, the .friction discs 56 and the housing discs 58 are mounted upon the bolt 52 so as to be freely rotatable thereon. A spider S having radially extending spring nger portions is mounted externally ofyeachof the disc assemblies upon opposite extending end portions of the bolt 52; and the spiders 60 are respectively mounted beneaththe bol-t head and the bolt nut so as to have their spring iingerrportions pressed thereby against the corresponding housing discs 58 so as to causethe .latter to be urged into frictional engagement with the corresponding bearing block and friction disc devices. A crank arm 65 extends radially fromeach of the housing discs 58 into pivotal connection at :6B with a linkl which in turn extends intopivotal connection at 68 with the Alugs.l8 extending from the gun Ill. Thus, upon reciprocation of thegun I0 relative to the bearer tubes l2-I2 the links 51 will cause the housing disosf58 to beoscillated relative to the fixed bearing blocks 4 Vwith the friction discs 56 oating therebetween, while the spider devices [i0 operate-to causethenscillating disc members to be pressed into frictional engagement against the .corresponding stationary 4 Y bearing blocks. It will be understood that the magnitude of the frictional forces thus developed will depend upon and may be regulated by adjustment of the nut of the bolt device 52.so that any desired degree of gun movement damping action may be obtained.

As illustrated in Figs. 5 and 6, the damping device of the gun mechanism may be conveniently'provided in another simplied vstructural form, and'for this purposethe-invention is similarly illustrated in conjunction with a machine gun 10 which is suitably mounted upon a pair of .bearer .tubes v'I2 for longitudinal reciprocation relativethereto in response to recoil forces of the ggunjfiring.operationfas explained hereinabove in :connection awith Figs. 1 to 4. For this purpose brackt'e'tf'ld which extends transversely of the gun intosliding connection at its opposite ends 15 with the bearer tubes 12. The recoil and return movement damping device is'designated generally at'jTB Aas .comprising Ya lever arm f80 which is pivotallymountedat one end by means ofa; pin lconnection82 to. a loracket..83 `which is xed tofone of the bearer vtubes .12. The :other lend V,of :the lever B0 terminates in an enlarged disc portion 85 which is centrally bored to receive Va boltf'l therethrough. Friction Ydiscs .88 are mounted upon the bolt ,81 v.at :oppositesides of the disc D.ortion, 85,.and.a pair of-crank-.plates having enlarged .disc-Shaped end .portions are pivotally mountedupon thebolt'l atopposite sides of the friction disc assembly. Y

At their opposite ends the crankarmsf-S yare pivotally connected vby means ofla .bolt-92 tothe transversebracket ,14; a. 'spacer 93 being vdisposed between corresponding outerend portions of the crank arms so as toimai'ntainfthem inparallel relationship. A ,spider 95 having radially V:extending spring ngers is lnlountedbelow'the nut of thebolt .81.50 .as lto beadaptedto be pressed byadjustmentof the nut against the-,disc'assembly of the damping device soas to provide frictional resistanc'ethereinto oscillation. of-.the lever arm "8D relative to the crankarmszll about the axis of the bolt 81. Thus, Vit will-'loe understood that upon development iof gun 4recoil and -return movement providing forces, asfexplained hereinabove, the gun '10 will becaused toAroscillate-relative to thebeareritube 1.2,-andithelever arm Yand crank elements of the damping mechanismwill be thereby causedtorelatively.oscillate aboutthe axis of theb'ltl.

Thus, it will be understood that the frictional resistance to relative movement developed within the friction ,disc .assembly Aportion of the-device provides constant .retarding Vand damping of gun movement ,forces :in connection lwith both rthe recoil .and counter-.recoil .motions of -the gun casing Lrelative -tothe gun barrel, .and that these retarding and damping effects are .experienced throughout the entire rangeof Vrecoil and counter-recoil movements. Thus, as .thebolt :mechanism of the gun retreats in response to the ammunition gas `expansion forces incidental -to the ring of each cartridge, .the corresponding recoil motions of the Ygun :casing are retarded by ,the :frictional damping mechanism so ,as .to bringthebolt and gun casing reciprocative'movements `into synchronized vbut Aout-of-phase relation. In fact, .the operation is suchasfto bring the bolt'and gun casing reciprocative movements into more 4,nearly lopp osedfdirectionareation, f compared :to `conventional .machine gun .arrangements. This produces a speeding-up of :the

cycles of the bolt actuations of the ejection and recharging mechanisms of the gun; and actual oscillograph tests of guns with and. without incorporation of the invention clearly show that the invention results in increasing the rate of bolt reciprocation (Which automatically determines the rate of firing) and decreases the gun mount reactions.

` For example, Fig. 7 of the drawing is a fragmentary reproduction of an actual oscillograph l0 record of the ring operation of a machine gun without the benefit of the present invention. Line A of the chart designates time elapse; line B records the recoil and counter-recoil force reactions in the gun mounting trunnion structure;

line C shows the timing and the amplitudes of the bolt movements; and line D records the timing and the amplitudes of the gun casing recoil movements, A study of this chart reveals that the bolt and gun casing reciprocative movements are (in the case 0f the conventional machine gun arrangement) substantially synchronized in directionally similar relation, and that the trunnion reaction forces are quite severe. Fig. 8 is a chart corresponding to Fig. 7 but recording similar data 25 in connection with a gun which incorporates the present invention; and a study of Fig. 8 shows that the bolt and gun casing recoil motions have been relatively rearranged and are now synchronized in directionally opposed relation, and

comparison of the two charts clearly reveals that in the case of the present invention the time of the bolt movement cycle has been substantially shortened (with a corresponding increase of the rate of gun fire), and that the severity of the gun trunnion reactions have been substantially lessened.

The important advantages and features of the invention explained hereinabove are obtained because of an automatic balancing of the reaction forces of the gun bolt and the gun casing portions; this balancing of the forces being attained by the frictional retarding and recoil damping actions of the mechanism described hereinabove.

Thus, it will be appreciated that the invention contemplates a recoil and counter-recoil control mechanism which coacts with both the gun casing and the gun bolt whereby to provide a gun operation of improved rate of re and of improved stability and steadiness throughout the firing operation.

In the drawing (Fig. 1) the invention is illustrated in conjunction with a U. S. Army designated 50 cal. M2 machine gun, of the type disclosed in U. s. Patent No. 1.628.226, having a ble to any other style of machine gun having a 6o reciprocating bolt action.

It will also be understoodfcf course that although only a few forms of the mechanism of the invention have been shown and described in detail, it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In combination, a machine gun having a casing, a reciprocable bolt in said casing, a, mount freely slidably supporting said casing, means biasing said casing with respect to said mount in opposition to recoil, means biasing said bolt with respect to said casing in opposition to recoil, and braking means interposed between said casing and mount for exerting a substantially constant resistance to relative movement thereof, said braking means including means for adjusting the value of said resistance with respect to said biasing means to adjust the recoil phase relationship of said bolt and casing.

2. In combination, a machine gun having a casing, a reciprocable bolt in said casing, a mount freely slidably supporting said casing, means biasing said casing with respect to said mount in opposition to recoil, Vmeans biasing said bolt with respect to said casing in opposition to recoil, and braking means interposed symmetrically between said casing and mount for exerting a substantially constant resistance to relative movement thereof, said braking means including means for adjusting the value of said resistance with respect to said biasing means to adjust the recoil phase relationship of said bolt and casing.

3. In combination, a machine gun having a casing, a reciprocable bolt in said casing, 4a mount freely slidably supporting said casing, means biasing said casing with respect to said mount and said bolt with respect to said casing in opposition to recoil, and braking means interposed between said casing and mount for exerting a substantially constant resistance to relative movement thereof, said braking means including means for adjusting the value of said resistance with respect to said biasing means to adjust the recoil phase relationship of said bolt and casing.

4. In combination, a machine gun having a casing, a reciprocable bolt in said casing, a mount freely slidably supporting said casing, independent springs biasing said casing with respect to said mount and said bolt with respect to said casing in opposition to recoil, and braking means interposed between said casing and mount for exerting a substantially constant resistance to relative movement thereof, said braking means including means for adjusting the value of said resistance with respect to said biasing means to adjust the recoil phase relationship of said bolt and casing.

JOHN C. TROTTER.

REFERENCES CITED VThe following references are of record in the le of this patent:

UNITED STATES PATENTS Number 

